Atrial fibrillation (AF) is the world?s most common serious heart rhythm problem and causes 15% of all strokes, a major cause of disability and death among Americans.1 Long-term monitoring for early AF detection and treatment is recommended for many stroke patients, but although existing cardiac monitors are accurate, they suffer from methodologic and cost limitations that preclude their long-term use. In the proposed, ?Smartwatch Monitoring for Atrial Fibrillation Real-Time in Stroke,? Study, our overall objective is to enhance paroxysmal AF (pAF) detection by enhancing and testing Pulsewatch, an innovative, smartwatch-based technology for long-term rhythm monitoring of stroke patients. For Aim 1, we embed our state-of-the art AF detection algorithms, interactive messaging to promote adherence, and novel contact and motion noise correction capabilities into a smartwatch to enable near-continuous pulse waveform analysis. We will further refine Pulsewatch through focus groups and a Hack-a-thon with stroke patients and their medical providers. For Aim 2, we will enroll 90 stroke survivors and provide them with a smartphone and smartwatch, both encoded with Pulsewatch. We will compare the performance of Pulsewatch when worn daily for 7 days to conventional 7-day cardiac monitoring for pAF detection. For Aim 3, we will determine the acceptability and usability of Pulsewatch through follow-up interviews and focus groups in 30 randomly selected participants from Aim 2 asked to continue wearing smartwatch daily for an additional 30 days. We will identify patient factors associated with adherence and evaluate the impact of Pulsewatch use on disease-specific quality of life, anxiety, and self- activation among the 30 users compared to 30 stroke patients treated with usual care through baseline and 1- month assessments. Our research will lead to the development of a highly acceptable, enabling cardiovascular monitoring technology designed by, and for, stroke patients that facilitates long-term non-invasive screening for pAF, as well as communication between stroke patients and their medical providers.